US6985764B2 - Flex circuit shielded optical sensor - Google Patents

Abstract

A flex circuit optical sensor has an integrated Faraday shield. A conductive trace layer disposed on a substrate is used to form a conductive grid which shields the face of a photodetector. A conductive ink layer is formed on a substrate side opposite the trace layer. The back and sides of the detector are shielded by flex circuit flaps that have the conductive ink layer but substantially exclude the trace layer so as to fold over and closely adhere to the detector body. The shielded substrate flaps advantageously eliminate a separate detector shield, which is typically fabricated with an etched copper part that must be attached to a flex circuit before mounting the detector.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims a priority benefit under 35 U.S.C. § 119(e) from U.S. Provisional Patent Application Nos. 60/288,324 entitled “Pulse Oximeter Sensor Attachment Flap,” filed May 3, 2001 and 60/301,183 entitled “Flex Circuit Shielded Optical Sensor,” filed Jun. 27, 2001, which are both incorporated by reference herein.

BACKGROUND OF THE INVENTION

Pulse oximetry is a widely accepted noninvasive procedure for measuring the oxygen saturation level of arterial blood, an indicator of a person's oxygen supply. Early detection of low blood oxygen level is critical in the medical field, for example in critical care and surgical applications, because an insufficient supply of oxygen can result in brain damage and death in a matter of minutes. A pulse oximetry system consists of a sensor applied to a patient, a pulse oximeter, and a patient cable connecting the sensor and the pulse oximeter. The pulse oximeter may be a standalone device or may be incorporated as a module or built-in portion of a multiparameter patient monitoring system and typically provides a numerical readout of the patient's oxygen saturation, a numerical readout of pulse rate, and an audible indicator or “beep” that occurs in response to each pulse. In addition, the pulse oximeter may display the patient's plethysmograph, which provides a visual display of the patient's pulse contour and pulse rate.

SUMMARY OF THE INVENTION

One aspect of a flex circuit shielded optical sensor is an emitter and detector mounted to a flex circuit. The emitter is configured to transmit optical radiation and the detector is configured to receive optical radiation from the emitter. A plurality of flap portions of the flex circuit each having an unfolded position extending from the flex circuit and a folded position at least partially enclosing the detector. In one embodiment, the flap portions comprise a back flap configured to fold over and adhere to a first portion of the detector and a side flap configured to fold over and adhere to a second portion of the detector. In another embodiment the flex circuit comprises a substrate layer having a first side and a second side and a conductive layer disposed on the second side substantially including the flap portions so that the flap portions in the folded position shield electromagnetic interference from the detector. The sensor may also comprise a trace layer disposed on the first side providing signal connections for the detector and the emitter. A conductive grid portion of the trace layer is proximate the flap portions and is configured to form a Faraday shield for the detector in conjunction with the flap portions. The trace layer may be substantially excluded from the flap portions.

Another aspect of a flex circuit shielded optical sensor is a flex circuit substrate having a first side and an opposite second side. A trace layer is disposed on the first side and has a pattern of conductors so as to electrically connect with an emitter and a detector. A conductive grid portion of the trace layer has at least one aperture so as to pass optical radiation from the emitter to the detector. The trace layer is configured to mount the detector proximate the grid portion. In one embodiment, the at least one aperture comprises at least one hole drilled through the substrate and the grid. In another embodiment, the substrate is adapted to transmit light and the at least one aperture comprises a pattern etched in the grid. In yet another embodiment, the optical sensor further comprising a shield layer disposed on the second side. The substrate has a foldable portion including the shield layer and substantially excluding the trace layer. The foldable portion is configured to substantially enclose the detector so as to form a Faraday shield in conjunction with the conductive grid portion. The foldable portion may have a plurality of flaps adapted to adhere to the detector. In a further embodiment, the sensor further comprises a stock material retaining the substrate and having a first wrap with a first end and a second wrap with a second end, where each of the wraps is adapted for finger attachment of the substrate. The wraps are configured so that the first end is covered by the second end and the second end terminates away from a person's palm.

A further aspect of a flex circuit shielded optical sensor is an optical sensor assembly method comprising the steps of fabricating an elongated flex circuit having a component side, an opposite side and a foldable portion. Other steps are creating a plurality of traces on the component side substantially excluding the foldable portion and creating a conductive layer on the opposite side substantially including the foldable portion. Further steps are mounting a detector and an emitter to the component side, where the traces provide electrical connections for the detector and the emitter, and disposing the foldable portion around the detector so as to shield the detector from electromagnetic interference. In one embodiment, the fabricating step comprises the substep of forming a back flap and a plurality of side flaps on the foldable portion. In another embodiment, the disposing step comprises the substeps of adhering the side flaps to first portions of the detector and adhering the back flap to second portions of the detector. In a further embodiment, the assembly method also comprises the step of creating a conductive grid portion of at least one of the traces. The mounting step may comprise the substep of positioning the detector proximate the grid portion so as to shield the detector from electromagnetic interference.

Yet another aspect of a flex circuit shielded optical sensor is a substrate means for supporting a flex circuit, a trace means disposed on a first side of the substrate means for connecting to a detector and an emitter, a conductive ink means disposed on a second side of the substrate for shielding the flex circuit, and a shield means including the substrate means and the conductive ink means for folding onto and attaching to the detector. In one embodiment, the optical sensor further comprises a grid means portion of the trace means for forming a Faraday shield around the detector. The grid means may comprise an aperture means for transmitting light to the detector. In another embodiment, the optical sensor further comprises a wrap means for finger attachment without an exposed wrap end on the palm-side of a finger.

For purposes of summarizing the invention, certain aspects, advantages and novel features of the invention have been described herein. Of course, it is to be understood that not necessarily all such aspects, advantages or features will be embodied in any particular embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A general architecture that implements the various features of the invention will now be described with reference to the drawings. The drawings and the associated descriptions are provided to illustrate embodiments of the invention and not to limit the scope of the invention. Throughout the drawings, reference numbers are re-used to indicate correspondence between referenced elements. In addition, the first digit of each reference number indicates the figure in which the element first appears.

FIGS. 1A–B are perspective views of a flex-circuit-shielded optical sensor;

FIGS. 2A–E are perspective views of a flex circuit shield folded to enclose an optical sensor detector;

FIGS. 3A–B are component side and non-component side views, respectively, of an optical sensor flex circuit;

FIG. 4 is a graphical depiction identifying the relative placement of various flex circuit layers;

FIGS. 5A–F are views of the various flex circuit layers;

FIG. 6 is a functional flowchart of flex circuit shielded optical sensor construction;

FIG. 7 is a component-side perspective view of a flex circuit panel;

FIGS. 8A–B are exploded and assembled perspective views, respectively, of a sensor core assembly;

FIG. 9A–E are top, sectional, bottom, front and perspective views, respectively, of a detector cavity; and

FIGS. 10A–B are an exploded view and a perspective view, respectively, of a sensor panel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Sensor Configuration

FIG. 1A illustrates one embodiment of a flex circuit shielded optical sensor. Thesensor100 has acentral body110, afoldover end130, aconnector end140, a pair of adhesive end attachment wraps150, a pair of adhesive middle attachment wraps160, aconnector180 and adetector housing190. The end wraps150 andmiddle wraps160 extend on either side of thecentral body110 and are used to attach thesensor100 to a patient's finger, in a manner similar to that described in U.S. Pat. No. 5,782,757 entitled “Low Noise Optical Probe,” which is assigned to the assignee of the present invention and incorporated by reference herein. Thecentral body110 retains a flex circuit assembly200 (FIGS. 2A–B), described in detail below. Theflex circuit assembly200 is a portion of a sensor core assembly800 (FIG. 8A–B), which is sandwiched into a completedsensor100, as described in detail with respect toFIGS. 8–10, below.

As shown inFIG. 1A, an emitter760 (FIG. 7) is located proximate a printedtarget112 that indicates finger placement. A detector740 (FIG. 7) is located in thedetector housing190. Thesensor100 is configured so that, when attached to a finger, the emitter760 (FIG. 7) projects light through the fingernail, through the blood vessels and capillaries underneath and into the detector740 (FIG. 7), which is positioned at the finger tip opposite the fingernail. Thesensor100 may also have an identification (ID) component780 (FIG. 7) with multiple uses depending on the manufacturer, such as an indicator of LED wavelength, sensor type or manufacturer. Theconnector180 electrically connects thesensor100 to a pulse oximetry monitor (not shown) via an associated mating connector on a patient cable (not shown).

Also shown inFIG. 1A in an unwrapped position, the middle wraps160 include ashort attachment wrap161 and anextended attachment wrap162. To attach the sensor to a person's finger, theshort attachment wrap161 is wrapped around the finger first. Theextended attachment wrap162 is then wrapped around theshort attachment wrap161, covering the shortattachment wrap end163. The extended attachment wrapend164 terminates away from the person's palm, such as on the side of the finger or, for small fingers, the back-of-the-hand. In this wrapped position, there are no wrap ends163,164 exposed on the person's palm. As such, the wrap ends163,164 of the middle attachment wraps160 are not prone to snag, attract debris or delaminate. In one embodiment, thesensor100 has anoptional extension110 to aconnector180. Alternatively, thesensor100 may have aconnector180 proximate the middle wraps160 with noextension110, such as shown inFIG. 1B, described below.

FIG. 1B illustrates another embodiment of a flex circuit shielded optical sensor. Thesensor100 has acentral body110, a printedtarget112, afoldover end130, aconnector end140, an adhesiveend attachment wrap150, a pair of adhesive middle attachment wraps160, aconnector180 and adetector housing190 and retains a flex circuit assembly200 (FIGS. 2A–B), as described with respect toFIG. 1A, above. As compared with the embodiment shown inFIG. 1A, theend wrap150 andmiddle wraps160 have greater surface area to achieve better finger adhesion. In particular, theend wrap150 is a generally rectangular, flared extension from thecentral body110 having rounded corners. The middle wraps160 include ashort attachment wrap161 and anextended attachment wrap162. Theextended attachment wrap162 is configured to wrap around theshort attachment wrap161 so that there are no wrap ends163,164 exposed on the person's palm, as described with respect toFIG. 1A, above.

FIGS. 2A–E illustrate aflex circuit assembly200. As shown inFIG. 2A, theflex circuit assembly200 has aflex circuit300, aconductive detector shield201, adetector740, anemitter760, and anID component780. Mounted on theflex circuit300 are theemitter760, having both red and infrared LEDs encapsulated on a leaded carrier, thedetector740 having a photodiode encapsulated on a leaded carrier and theID component780 such as a resistor on a leadless carrier. Theflex circuit300 is described in detail with respect toFIGS. 3–5, below. Mounting of thecomponents740,760,780 is described in further detail with respect toFIG. 7, below.

FIGS. 2A–E also illustrate the folding of thedetector shield201 around thedetector740. As shown inFIG. 2A, thedetector shield201 is an integral portion of theflex circuit300 and is located at one end of theflex circuit300 proximate thedetector740. Theshield201 has aback flap210 and a pair of side flaps230, which have an unfolded position and a folded position. In the unfolded position illustrated inFIG. 2A, theflaps210,230 extend from theflex circuit300. In the folded position illustrated inFIGS. 2D–E, each of theflaps210,230 at least partially enclose thedetector740.

As shown inFIG. 2B, the side flaps230 are folded toward and adhere to the sides of thedetector740. As shown inFIG. 2C, theback flap210 is also folded toward and adheres to the top of thedetector740. As shown inFIG. 2D, theback flap210 is also folded over thedetector740 and adheres to the back face of thedetector740 and the surface of theflex circuit300. As shown inFIG. 2E, thedetector shield201 is configured to substantially enclose thedetector740 in conjunction with a conductive grid310 (FIG. 3A), acting as a Faraday shield to limit electromagnetic interference (EMI) reaching thedetector740. Thedetector shield201 and conductive grid510 (FIG. 3A) are described in further detail with respect to FIGS.3A and5D–F, below.

FIGS. 3A–B illustrate one embodiment of theflex circuit300, which has anelongated body302 widened at aconnector end304 and anopposite shield end303. Thedetector shield201, as described with respect toFIGS. 2A–E, above, is located at theshield end303. Between theends303,304 is a widenedbody portion305 having anemitter aperture308. Thebody302 has a component side301 (FIG. 3A) and a non-component side306 (FIG. 3B). Theflex circuit300 is made up of multiple conducting and insulating layers, as described with respect toFIGS. 4–5, below.

As shown inFIG. 3A, the flexcircuit component side301 has aconductive grid510, adetector pad520, anemitter pad530, anID pad540 and connector traces550. Theemitter pad530 andID pad540 are exposed throughcoverlays410,430 (FIG. 4) at anemitter pad aperture330 and anID pad aperture340, respectively. The detector740 (FIG. 7), emitter760 (FIG. 7) and ID780 (FIG. 7) components are mounted to theflex circuit300 at thedetector520,emitter530 andID540 pads, as described with respect toFIG. 7, below. Thedetector shield201 has a back flap pressure sensitive adhesive (PSA)372 and aside flap PSA374 that allow theshield201 to adhere to the detector740 (FIG. 7), as described with respect toFIGS. 2A–E, above.

As shown inFIG. 3B, thenon-component side306 has acover PSA382 and acavity PSA384 that adhere inside the detector housing190 (FIG. 1) and also atab PSA388 that adheres to the connector tab820 (FIG. 8A), as described with respect toFIGS. 8A–B, below. The conductive grid510 (FIG. 3A) hasapertures512 that allow light to reach the detector740 (FIG. 7). Specifically, light is transmitted from the emitter component760 (FIG. 2A), through theemitter aperture308, through a fingernail bed and exits from a fingertip, entering the detector housing190 (FIG. 1) and into thedetector grid510 to be received by the detector740 (FIG. 7). Theflex circuit300 has printed traces of deposited or etched conductive material, described with respect toFIG. 5D, below.

FIG. 4 illustrates the layered structure of theflex circuit300, which includes atop coverlay410, atop ink layer420, aninner coverlay430, atrace layer440 and asubstrate layer460, abottom ink layer470, abottom coverlay480, aPSA layer490 and arelease liner496. Thetrace layer440 consists of conductive material carried on an insulatingsubstrate460. Thetrace layer440 has a trace pattern that defines aconductive grid510, adetector pad520, anemitter pad530, anID pad540,connector contacts550 and associated interconnects. In a particular embodiment, thetrace layer440 andsubstrate layer460 are constructed from a single sided 1 oz. rolled/annealed copper clad 1 mil. polyimide film, and a trace pattern is etched from the copper accordingly. Thebottom ink layer470 is carried on the opposite side of the insulatingsubstrate460, and, in a particular embodiment, is DUPONT CB028 silver-filled thermoplastic screenable ink. Theinner coverlay430 carries thetop ink layer420 and insulates it from thetrace layer440. Thru-holes in theinner coverlay430 andsubstrate460 provide selective connections betweentrace layer440, thetop ink layer420, and thebottom ink layer470. Thetop coverlay410 andbottom coverlay480 provide insulating protection for thetop ink layer420 and thebottom ink layer470. ThePSA layer490 and therelease liner layer496 provide the cover, cavity andtab PSA382,384,388 (FIG. 3B). Similar layers (not shown) on thetop coverlay410 provide thedetector shield PSA372,374 (FIG. 3A). In a particular embodiment, thecoverlays410,430,480 are 1 mil polyimide and the PSA is 3M-467MP. Theselayers410–470 are described in further detail with respect toFIGS. 5A–F, below.

FIGS. 5A–F illustrate the flex circuit layers identified with respect toFIG. 4, above.FIG. 5A illustrates thetop coverlay410 positioned relative to the substrate460 (dashed outline). Thetop coverlay410 is an insulating film having anemitter aperture308, anemitter pad aperture330 and anID pad aperture340. Theemitter aperture330 allows light from the emitter760 (FIG. 7) to pass through thecoverlay410 and other layers. Theemitter pad aperture330 andID pad aperture340 expose the emitter pad contacts530 (FIG. 3A) and ID pad contacts540 (FIG. 3A) for attachment of the emitter760 (FIG. 7) and ID component780 (FIG. 7). In one embodiment, thetop coverlay410 is 1 mil polyimide.

FIG. 5B illustrates thetop ink layer420 positioned relative to the substrate460 (dashed outline) and the inner coverlay430 (solid outline). The top ink layer420 (filled area) is applied to theinner coverlay430 with a pull back422 around the periphery of theinner coverlay430.Additional pullbacks424 are around the peripheries of the emitter aperture308 (FIG. 5C), the emitter pad aperture330 (FIG. 5C) and the ID pad aperture340 (FIG. 5C). In one embodiment, the top ink layer is DUPONT CB028 silver-filled thermoplastic screenable ink and thepullbacks422,424 are a minimum 25 mil.

FIG. 5C illustrates theinner coverlay430 positioned relative to the substrate460 (dashed outline). Theinner coverlay430 is an insulating film having anemitter aperture308, anemitter pad aperture330 and anID pad aperture340, corresponding to those described with respect to the top coverlay410 (FIG. 5A), above. Theinner coverlay430 has thru-holes432,434,436 that allow the top ink layer420 (FIG. 5B) to electrically connect with portions of the trace layer440 (FIG. 5D). In particular, an upper thru-hole432 and a middle thru-hole434 provide connections to a grid trace590 (FIG. 5D), and a lower thru-hole436 provides a connection to a guard trace580 (FIG. 5D).

FIG. 5D illustrates thetrace layer440 positioned relative to the substrate460 (dashed outline). Thetrace layer440 is advantageously substantially excluded from theflap portions461,465 (FIG. 5E) of thesubstrate layer460, allowing theflaps210,230 (FIGS. 2A–E) to fold over and closely adhere to the detector740 (FIGS. 2A–E) without obstruction from circuit components, conductors and connectors. Thetrace layer440 has adetector grid510, adetector pad520, anemitter pad530, anID pad540, andconnector contacts550. Thegrid510 has agrid conductor512 that provides an EMI shield for the detector740 (FIG. 7) in conjunction with the flex circuit shield201 (FIG. 3A). Thegrid510 also hasgrid apertures514 that allow light to reach the detector740 (FIG. 7). Detector traces560 electrically connect adetector pinout portion561 of thecontacts550 to thedetector pad520. Emitter traces570 electrically connect anemitter pinout portion571 of thecontacts550 to theID pad540 and theemitter pad530. Aguard trace580 extends from ashield pinout portion581 of thecontacts550 proximate the detector traces560 to a stub proximate thedetector pad520. Agrid trace590 extends from thegrid510 to a stub proximate theconnector contacts550.Grid pads592,594 provide an electrical connection via thru-holes432,434 (FIG. 5C) and thru-holes462,464 (FIG. 5E) at either end of thegrid trace590 to the top ink layer420 (FIG. 5B) and bottom ink layer470 (FIG. 5F). Aguard pad582 provides for an electrical connection via a thru-hole436 (FIG. 5C) and a thru-hole466 (FIG. 5E) at one end of theguard trace580 to the top ink layer420 (FIG. 5B) and bottom ink layer470 (FIG. 5F), respectively.

FIG. 5E illustrates thesubstrate layer460, which has backflap461 and side flaps465 that are the substrate layer portions of the shield back flap210 (FIGS. 2A–E) and side flaps230 (FIGS. 2A–E), respectively. Thesubstrate layer460 also hasindents463 that narrow the substrate between theback flap461 and the side flaps463, allowing theback flap461 to fold as described with respect toFIGS. 2A–E, above. Further, thesubstrate layer460 hasslots467 on the opposite end of the side flaps465 from theindents463 that, in conjunction with theindents463 allow the side flaps465 to fold as described with respect toFIGS. 2A–E, above. In addition, thesubstrate layer460 hasgrid apertures514 and anemitter aperture308, described with respect toFIGS. 3A–B, above. Substrate thru-holes462,464,466 are drilled to allow the bottom ink470 (FIG. 5F) to connect with portions of the trace layer440 (FIG. 5D), as described above.

FIG. 5F illustrates thebottom ink layer470 positioned relative to the substrate460 (solid outline). Thebottom ink layer470 is advantageously substantially included on theflap portions461,465 (FIG. 5E) of thesubstrate layer460, allowing theflaps210,230 (FIG. 2A–E) to shield the detector740 (FIGS. 2A–E) from electromagnetic interference. The bottom ink layer470 (filled area) is applied to thesubstrate460 with a pull back472 around the periphery of thesubstrate460 except in ashield area474 proximate the detector end of the substrate. Thebottom ink layer470 also has a pull back476 around theemitter aperture308. In one embodiment, the bottom ink layer is DUPONT CB028 silver-filled thermoplastic screenable ink and the pullback is a minimum 25 mil.

Sensor Fabrication

Flex Circuit Assembly

FIG. 6 illustrates general construction steps600 for a flex-circuit-shielded optical sensor100 (FIG. 1). As represented by a fabricate flex circuitpanel activity block610, multiple flex circuits300 (FIGS. 3A–B) are formed on a panel constructed of multiple layers400 (FIG. 4), as described above. In a particular embodiment, a 7-up panel layout is used. Represented by an attach panelcomponents activity block620, panel components are attached to each of the multiple flex circuits on a panel700 (FIG. 7).

FIG. 7 illustrates the flex-circuit panel fabrication and panel component attachment. Multiple flex circuits are formed by etching a pattern of conductors in the trace layer440 (FIG. 4), which creates a circuit as described with respect toFIG. 5D, above. Thru-holes are drilled in the inner coverlay430 (FIG. 4) and substrate460 (FIG. 4), as described with respect toFIGS. 5C,5E, above. The inner coverlay430 (FIG. 4) and substrate460 (FIG. 4) layers are laminated. Conductive ink is screened onto the inner coverlay430 (FIG. 4) and substrate460 (FIG. 4) as described with respect toFIGS. 5B and 5F, above. The remaining layers are laminated. Thecontacts550 are selectively electroplated with gold. In a particular embodiment, the plating is 10 micro inches minimum of hard gold using a pulse plating method over 75±25 micro inches of nickel. Grid aperture holes514 are drilled. Thedetector740,emitter760 andID780 components are electrically connected to thepanel pads520,530,540.

As shown inFIG. 6, represented by a die-cutpanel activity block630, the flex circuit panel700 (FIG. 7), described above, is die-cut to separate individual flex circuits200 (FIGS. 2A–E). Represented by a fold shield overdetector activity block640 theshield201 of eachflex circuit assembly200 is folded so as to enclose the detector740 (FIG. 7) and shield it from EMI, as described with respect toFIGS. 2A–E, above.

Sensor Core Assembly

Also shown inFIG. 6, a place cavity on basestock activity block651, a place connector tab on basestock activity block655 and a place flex circuit on basestock activity block660 represent attachment of the detector cavity900 (FIG. 9) and the connector tab820 (FIG. 8A) to the flex circuit assembly200 (FIG. 8A). A place disk and cover overcavity activity block670 represents completing the detector housing190 (FIG. 8B) to finish a sensor core assembly800 (FIG. 8A–B) as described below.

FIGS. 8A–B illustrate thesensor core assembly800, which has aflex circuit assembly200, including a folded over flexcircuit detector shield201, as described with respect toFIGS. 2A–E and 7, above. Thesensor core assembly800 also has aconnector tab820, adetector cavity900, an opaqueoptical disk830 and acover840. Theconnector tab820 attaches with tab PSA388 (FIG. 3B) behind theconnector contacts550, forming aconnector plug180 configured to engage and electrically connect with a patient cable connector socket (not shown) as described in U.S. Pat. No. 5,782,757, referenced above. Theconnector tab820 has anaperture821 that catches onto a latching portion of the mating socket. In a particular embodiment, theconnector tab820 is fabricated of an ABS polymer blend.

As shown inFIGS. 8A–B, thecavity900,disk830 and cover840 form adetector housing190 that retains the detector740 (FIG. 7) and correspondingflex circuit shield201. Thecavity900 provides areceptacle920 for the shielded detector740 (FIG. 7) and secures theshield201 against the detector740 (FIG. 7), as described with respect toFIGS. 9A–E, below. Cavity PSA384 (FIG. 3B) adheres a portion of theflex circuit assembly200 inside thecavity900. Thecover840 fits over thecavity900 to physically retain the detector740 (FIG. 7) and to seal out ambient light. Anopaque disk830 provides further ambient light protection and, in one embodiment, is a metal foil. Cover PSA382 (FIG. 3B) adheres thedisk830 and cover840 to theflex circuit assembly200. Thecover840 has aflange842 that serves as a bonding surface for base stock1010 (FIG. 10A) and face stock1020 (FIG. 10A) material. In one embodiment, thecover840 is vacuum formed from polystyrene and has an opaque characteristic obtained from coating or from its construction material.

FIGS. 9A–E illustrate adetector cavity900, which has aramp910, arectangular receptacle920, alignment guides comprising aback guide932 and two side guides934 and acavity aperture940. Therectangular receptacle920 is adapted to receive the detector end of the flex circuit assembly200 (FIGS. 8A–B). Theramp910 is wedge-shaped and provides for a smooth transition for the flex circuit assembly200 (FIGS. 8A–B) between the surface of the base stock1010 (FIG. 10A) and the surface of therectangular receptacle920. The alignment guides932,934 hold the flex circuit assembly200 (FIGS. 8A–B) in position so that the detector740 (FIG. 7) aligns properly with theaperture940. Also, theback guide932 secures the back flap210 (FIGS. 2A–E) and the side guides934 secure the side flaps230 (FIGS. 2A–E) against the detector740 (FIGS. 2A–E). Theaperture940 stabilizes a finger within the sensor so as to reduce optical decoupling between the emitter and the detector, avoids compression of finger tissue so as to stabilize the optical path length through the finger, and reduces light-piping, i.e. direct coupling of light between the detector740 (FIG. 7) and emitter760 (FIG. 7), as described with respect to U.S. Pat. No. 5,782,757, referenced above. In one embodiment, thecavity900 is made from an ABS polymer blend and has an opaque characteristic obtained from coating or from its construction material. In a particular embodiment, theaperture940 is conical or cylindrical in shape.

Sensor Panel Assembly

Further shown inFIG. 6, represented by a place face stock over basestock activity block680, the face stock1020 (FIG. 10A) placement over the base stock1010 (FIG. 10A) retains the sensor assembly800 (FIG. 8B) within the stock material, as described with respect toFIGS. 10A–B, below. As represented by a die-cut sensor panel to finalshape activity block690, individual sensors100 (FIG. 10B) are cut from the sensor panel1000 (FIGS. 10A–B), as described below. In a particular embodiment, the sensor panel1000 (FIGS. 10A–B) is configured for two sensors100 (FIG. 10B).

FIGS. 10A–B illustrate asensor panel1000, which has a base stock1010 and aface stock1020 enclosing multiplesensor core assemblies800. As shown inFIG. 10A, the base stock1010 is a flexible material that is transparent to the wavelength of the emitter. In an alternative embodiment, the base stock1010 has holes corresponding to the emitter apertures308 (FIGS. 3A–B) and grid apertures514 (FIG. 5E) of thesensor core assemblies800. The base stock1010 has PSA on thebase stock side1012 to which theface stock1020 is applied. In one embodiment, theface stock1020 is a flexible woven material, such as Betham part no. 1107S. Theface stock1020 hashousing apertures1022 that allow portions of the detector housing covers840 to protrude through theface stock1020. In one embodiment, theface stock1020 has PSA on the side (not visible) facing the base stock1010. Asensor panel1000 is created by sandwiching thesensor core assemblies800 between the base stock1010 and theface stock1020 and applying pressure so that the base stock1010 and facestock1020 bond together, retaining thesensor core assemblies800.

As shown inFIG. 10B, the assembledsensor panel1000 is cut and the excess material discarded to completemultiple sensors100. In one embodiment, a completedsensor panel assembly1000 forms twosensors100.

The flex circuit shielded optical sensor has been disclosed above with respect to a polyimide substrate supporting a copper trace layer. A detector Faraday shield has a detector grid portion fabricated from the copper trace layer and aperture holes drilled through the substrate and the grid so as to allow light to be received by the detector. In an alternative embodiment, a polyester nitrile (PEN) substate supports the copper trace layer. The grid has an aperture pattern etched in the trace layer rather than drilled aperture holes. The PEN material is clear, allowing light to pass to the detector while maintaining mechanical strength in the grid area.

Although the flex circuit shielded optical sensor has been described in terms of certain preferred embodiments, other embodiments will be apparent to those of ordinary skill in the art from the disclosure herein. Moreover, these embodiments are disclosed by way of examples only and are not to limit the scope of the claims that follow. One of ordinary skill in the art will appreciate many variations and modifications.

Additionally, all publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference.

Claims (12)

1. An optical sensor comprising:

a flex circuit substrate having a first side and an opposite second side;

a trace layer disposed on said first side having a pattern of conductors so as to electrically connect with an emitter and a detector,

a conductive grid portion of said trace layer having at least one aperture so as to pass optical radiation from said emitter to said detector, said trace layer configured to mount said detector proximate said grid portion;

a shield layer disposed on said second side, said substrate having a plurality of foldable portions including said shield layer and substantially excluding said trace layer, said plurality of foldable portions being configured to substantially enclose said detector so as to form a Faraday shield in conjunction with said conductive grid portion.

2. The optical sensor according toclaim 1 wherein said plurality of foldable portions comprise a plurality of flaps adapted to adhere to said detector.

3. The optical sensor according toclaim 1 further comprising:

a stock material retaining said substrate and having a first wrap with a first end and a second wrap with a second end,

each of said wraps adapted for finger attachment of said substrate,

said wraps configured so that, in a wrapped position, said first end covers said second end and said second end terminates distal to a person's palm.

4. An optical sensor assembly method comprising the steps of:

fabricating an elongated flex circuit having a component side, an opposite side and a plurality of foldable portions;

creating a plurality of traces on said component side substantially excluding said plurality of foldable portions;

creating a conductive layer on said opposite side substantially including said plurality of foldable portions;

mounting a detector and an emitter to said component side, said traces providing electrical connections for said detector and said emitter; and

disposing said plurality of foldable portions around said detector so as to shield said detector from electromagnetic interference.

5. The optical sensor assembly method according toclaim 4 wherein said step of fabricating the plurality of foldable portions step comprises the substep of forming a back flap and a plurality of side flaps.

6. The optical sensor assembly method according toclaim 5 wherein said disposing step comprises the substeps of adhering said plurality of side flaps to first portions of said detector and adhering said back flap to second portions of said detector.

7. The optical sensor assembly method according toclaim 4 further comprising the step of creating a conductive grid portion of at least one of said traces.

8. The optical sensor assembly method according toclaim 7 wherein said mounting step comprises the substep of positioning said detector proximate said grid portion so as to shield said detector from electromagnetic interference.

9. A noninvasive disposable optical sensor which outputs a signal usable to determine one or more physiological parameters, the optical sensor comprising:

at least one emitter;

a light sensitive detector capable of detecting light emitted from the at least one emitter and attenuated by body tissue, said detector also capable of outputting a signal usable to determine one or more physiological parameters of the body tissue;

a flexible circuit comprising the at least one emitter, the detector, an interconnect layer, and a substrate layer, wherein the substrate layer is formed from a unitary structure including a plurality of foldable portions extending from a main body portion, and wherein the foldable portions fold over and around the detector while the main body portion substantially covers the interconnect layer, thereby substantially enclosing and shielding the light sensitive detector from external noise; and

adhesive attachment wraps capable of adhering the disposable optical sensor to the body tissue, wherein the plurality of foldable portions of the flexible circuit are different from the adhesive attachment wraps and wherein the plurality of foldable portions are not used for attachment of the disposable optical sensor to the body tissue.

10. The optical sensor ofclaim 9, wherein the disposable optical sensor is part of a patient monitoring system including a patient monitor capable of receiving the signal from the disposable optical sensor and determining the one or more physiological parameters.

11. A method of assembling a multi-layer optical sensor comprising:

fabricating a multi-layer circuit panel including a trace layer and at least one of a top ink layer and a bottom ink layer, wherein the trace layer comprises a plurality of conductive traces;

separating the multi-layer circuit panel into a plurality of multi-layer elongated flexible circuits, wherein each flexible circuit includes a plurality of foldable portions substantially free of the plurality of conductive traces;

mounting a detector and at least one emitter to each flexible circuit, wherein the conductive traces provide electrical connections for each detector and each emitter;

disposing the foldable portions around each detector so as to shield each detector from electromagnetic interference;

attaching sensor panel material to the flexible circuits; and

shaping the sensor panel material into multi-layer optical sensors, wherein the shapes assist in attachment of each optical sensor to a measurement site.

12. The method according toclaim 11, further comprising the multi-layer circuit panel including the other of the top ink layer and the bottom ink layer.

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